AMCI SMD34K, User Manual

Page: 14 / 100

SMD34K S
PECIFICATIONS
SMD34K User Manual
ADVANCED MICRO CONTROLS INC.
14
Indexer Functionality (continued)
Immediate Stops
If a move is in progress when an Immediate Stop command is issued, the SMD34K responds
by shorting the motor’s windings together. This forces any regeneration energy to be dissi-
pated in the windings instead of being reflected back into the power supply. The windings can
be shorted for up to 300 milliseconds. Once the short is removed, the SMD34K will set a bit in
the network input data named
Stopped , to show that motion is stopped and the unit is ready to
accept your next command.
Synchronizing Moves
By default, the SMD34K products use the SyncManager 2 event to control the transfer of data from the Ether-
CAT Slave Controller (ECS) to the microprocessor that controls motion. This allows the SMD34K to execute
commands as soon as new data arrives. When more than one axis is updated with a single EtherCAT packet,
the time difference between axis updates is very short. Updating multiple axes with a single packet allows the
EtherCAT network to out perform the update times of other industrial network protocols.
On very fast machines, or large machines that require more than one transfer to update all axes, the EtherCAT
Distributed Clock (DC) functionality can be used to closely synchronize motion over multiple axes if using
the SyncMaster2 event proves to be ineffective.
The EtherCAT Distributed Clock functionality is built into the ECS used by the SMD34K products. The
SMD34K can act as the reference clock for the system if it is the first device in the EtherCAT network. The
SYNC0 signal, which is based off of the Distributed Clock, can be use to synchronize the start of moves over
multiple devices. The time between when the SYNC0 signal is received by the main processor of the
SMD34K and when the driver begins to cause motion is 520 ± 25 microseconds. The 520 microseconds is
the time required to read the data from the ECS once the SYNC0 signal becomes active. The ±25 microsec-
onds is caused by the 20 kHz update frequency of the PWM drivers.
For the SMD34K, the minimum update time on the SYNC0 signal is two milliseconds. If the task time is less
than two milliseconds, the SYNC0 time must be a multiple of the task time.
In order to improve performance, the SYNC0 signal is brought into the main processor as
Input 3. When using the Distributed Clock (DC) functionality, Input 3 is unavailable for use
and an external connection to it must not be made.
Additional Notes on Stall Detection
When Stall Detection is enabled, the SMD34K monitors the encoder for position changes, regardless of
whether or not a move is in progress. If the error between the encoder position and the motor position exceeds
forty-five degrees, the SMD34K responds in the following manner:

The stall is reported in the network input data.

The motor position becomes invalid. (The machine must be homed or the motor position preset before
Absolute moves can be run again.

If a move was in progress, the move is stopped.
Note that a move does not have to be in progress for stall detection to be useful. As described later in this
chapter, there is an auxiliary power pin, DCPower
AUX
, that powers the electronics of an SMD34K but does
not power the motor. The DCPower
MAIN
pin powers both the electronics and the motor. The primary use of
the DCPower
AUX
feature is to keep the unit on the network while power is removed from the motor. By
enabling stall detection, the SMD34K can notify the system if the motor shaft moves more than forty-five
degrees while main power is removed from the motor.